// Source: <https://github.com/parcel-bundler/parcel/blob/master/packages/core/parcel-bundler/src/builtins/bundle-url.js>

let bundleURL: string | undefined

function getBundleURLCached(): string {
  if (!bundleURL) {
    bundleURL = getBundleURL()
  }

  return bundleURL
}

function getBundleURL(): string {
  // Attempt to find the URL of the current script and use that as the base URL
  try {
    throw new Error('getBundleURL failed')
  } catch (ex) {
    const err = ex as Error
    const matches = ('' + err.stack).match(/(https?|file|ftp|chrome-extension|moz-extension):\/\/[^\n)]+/g)
    if (matches) {
      return getBaseURL(matches[0])
    }
  }

  return '/'
}

function getBaseURL(url: string): string {
  return ('' + url).replace(/^((?:https?|file|ftp|chrome-extension|moz-extension):\/\/.+)?\/[^/]+(?:\?.*)?$/, '$1') + '/'
}

export { getBundleURLCached as getBundleURL }